Matthew J. Murphy, Biological Sciences
“How Black are Blackbirds? An Analysis of Plumage Darkness and Habitat in Icteridae”
Faculty Mentor: Dr. Kevin Omland
Expected Graduation Date: May 2010
The family of chemicals known as melanins is the primary source of dark pigments in animals. Organisms vary widely in the amount of melanin they express, some expressing little or no dark pigment while others are completely black. Such a wide spectrum of traits suggests that there are strong selectors involved in determining a species’ average amount of dark pigment. A hypothesis, called Gloger’s Rule, has been proposed which attempts to explain this wide variety of traits and introduces a basis for selection based on the darkness of an organism’s hair, feathers, or skin. Working in collaboration with the UMBC chemistry department and the Smithsonian Museum of Natural History, I will measure the relative eumelanin and phaeomelanin concentrations in feather samples from many species of the New World blackbirds (Icteridae). Using this data, I will test Gloger’s Rule, a hypothesis that endothermic (warm-blooded) animals tend to be dark in more humid climes, particularly around the equator. In addition, I will investigate the degree of evolutionary plumage lability within this taxon, using a molecular phylogeny of New World Icterids published by Dr. Omland (Lanyon and Omland 1999).